In recent years, there has been developed, as a suspension system for a vehicle, the so-called electromagnetic suspension system including an electromagnetic actuator configured to apply, to a sprung portion and an unsprung portion, a force in a direction in which the sprung portion and the unsprung portion are moved toward and away from each other. For instance, the following Patent Documents disclose such an electromagnetic suspension system. Each of the disclosed suspension systems is expected as a high-performance suspension system in view of an advantage that it is possible to easily realize a suspension characteristic based on the so-called skyhook theory.    Patent Document 1 JP-A-2003-104025    Patent Document 2 JP-A-2003-42224